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A Study of Efficiently Dynamic Updating Algorithm and Experiments for Tessellation by Triangulation of Huge Data Sets

Author: HuHaiYan
Tutor: YuXuChu；FangYong
School: PLA Information Engineering University
Course: Photogrammetry and Remote Sensing
Keywords: Triangular grid Algorithm Data structure Delaunay Dynamic editing DEM Digital photogrammetry
CLC: P224.2
Type: Master's thesis
Year: 2007
Downloads: 130
Quote: 1
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Abstract

The triangular grid digital elevation model (Digital Elevation Model, DEM) is one of the most scientific formulation in the the DEM many forms of expression, but result in the application is limited due to its theory and the complexity of the software implementation. As most of the domestic digital photogrammetry system triangular grid DEM dimensional \It is from this type of application requirements and carried out research and innovations are as follows; 1. Clarify the concept, characteristics and scope of application of the triangular grid. Summarizes Delaunay triangular mesh to build the current situation and existing problems of the algorithm; existing algorithms generally not practical conceptual algorithm can not meet the large amount of data, adaptive the point bit random distribution does not meet the efficient dynamic editing and other practical requirements. 2. Involving triangular mesh, Delaunay triangular mesh theory in particular, in-depth study, summed up the three main characteristics of the Delaunay triangulation mesh; minimum angle (max-min angle), the geometric positions degradation point set is still meet the minimum angle of the largest regions of conflict (conflict area) with partial reconnection (local reconnection). Postorder algorithm design has theoretical significance, in which the partial reconnection characteristics affect the efficiency of the implementation of the algorithm bottleneck section gives the theoretical basis of the optimization method. According to the demand points, how to quickly build the spatial structure of the optimal Delaunay triangulation grid as well as how to efficiently edit (add, delete vertex), combines geometric theory and the theory of randomized algorithms, an increase in the existing triangular mesh amount stochastic dynamic Delaunay triangular mesh construction algorithm, the the algorithms process is complete and informative. The algorithm is the adaptability of the large amount of data, randomness efficient dynamic editing features, a comprehensive analysis and the performance of the algorithm; algorithm data structure space complexity is linear order O (n); net lattice building algorithm time complexity of the \class optimal solution of the problem. The analysis results show that; algorithm has realized the value. Write programs be implemented algorithm design, developed Delaunay triangular mesh function package, and software to carry out a comprehensive and rigorous testing experiment, test results confirmed the validity of the conclusions of algorithm analysis. Random selection of 10,000 to 100,000 in the three-dimensional space of the experiment point set test configuration rapidity, the statistics of a single point of insertion and deletion time; meet the circle with the point distribution curve point set of special functions to test the software for geometric degradation adaptability, the results are correct, the entire testing process to verify the robustness of the software. 5. Comparing the accuracy and efficiency of the implementation are inferior to the current package of two application examples - the stereoscopic Online triangular mesh DEM dynamic acquisition, editing and DEM format conversion, and existing commercial software commercial software, initially demonstrated the value of the development package. 6 summarizes the research content given the outlook further restricted Delaunay triangulation mesh technology research direction, and give instructions on the next step of the software development to achieve the function.

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